The present invention relates to powered wrenches. In particular, the present invention pertains to portable powered wrenches that can be carried and applied with two hands at a variety of locations to provide torque, such as for exercising valves on fire hydrants. Such portable powered wrenches are often called valve testers or valve exercisers.
There are a wide variety of situations wherein wrenches are used to provide torque, such as to a nut or to the head of a bolt. The vast majority of these situations involve a relatively small hand-held tool intended for single handed operation, providing a moment arm on the tool totaling 18 inches or less from the axis of rotation. Some of these single handed tools also include a small motor for providing a turning force, so the wrench can rotate the subject without movement of the handle.
Some applications require more torque than a small, single-hand tool can readily deliver. For some of these larger applications, tools to provide torque are not hand-held, but rather are mounted on vehicles or stands. However, each use of such larger tools requires positioning of the vehicle or stand relative to the driven member, which can be difficult and time consuming. Vehicle or stand support structures also typically add considerable expense to the tool.
The present invention is directed to intermediate applications, where the torque required is significant but can still be applied by a portable handheld tool. A particular application where this is the case involves exercising of fire hydrant valves. Fire departments regularly exercise fire hydrant valves to ensure that the fire hydrants are operational should a need arise. Typically the torque required to open such valves has a peak in the range of 50-250 ft-lbs, and a full exercise involves five to twenty 360° rotations of the valve nut on the fire hydrant. While it is possible to perform these valve exercisings with a manually powered tool, the forces and repetitive stresses involved can lead to injuries of the workers. Accordingly, several companies have proposed solutions involving portable, hand-held, powered tools which can be used for exercising fire hydrant valves, such as Wm. F. Hurst Co., Inc. of Wichita, Kans., Singleton Equipment, LLC of Livingston, La. and E.H. Wachs Company of Harvard, Ill. The existing solutions have created problems of their own however and don't adequately consider operator safety, and better solutions are needed.